Stroke is a major public health problem, with a US mortality rate that ranks third behind other diseases involving the cardiovascular system and cancer. We propose to pursue neuroprotection in ischemic stroke by targeting a key regulator of Ca2+ homeostasis, Ca2+/CaM-dependent protein kinase II (CaMKII). Inhibition of CaMKII represents a novel paradigm in ischemic stroke-neuroprotection based on blocking the effects of CaMKII on Ca2+ overload as well as its more direct effect on mediators of neurotoxicity. Two developments provide us with the rationale and opportunity to test potent small molecule CaMKII inhibitors in ischemic stroke. First, hyperactivity of CaMKII has been shown to promote cell death in glutamate excitotoxicity while inhibitors of the kinase are neuroprotective in situ and in the middle cerebral artery occlusion (MCAO) model. Second we have taken the opportunity to restart a CaMKII inhibitor program initially advanced at a pharm and which we are now accelerating based on insights from the first crystal structures of the human enzyme. Our proposal is relatively straightforward, to increase CNS penetration of the potent inhibitors we developed and test the optimized lead compound in a permanent occlusion MCAO model. We have designed a number of modifications that increase lipophilicity of our compounds with the aim of increasing their CNS penetration. The compounds will be analyzed for kinase inhibition and selectivity in vitro, and for inhibition and protection from glutamate excitotoxicity in neuronal cultures. The inhibitor with the greatest potential for CNS penetration will be selected based on bidirectional permeability through MDR----MDCK monolayers and its brain/plasma distribution in vivo will be quantified. The lead CNS penetrating inhibitor will be tested in the rat permanent occlusion MCAO model. We will monitor the degree of CaMKII inhibition achieved in vivo using biomarkers of kinase activity and quantify the effect of the inhibitor on infarct size. A successfully proof----of----concept in ischemic stroke will position us for a Phase II SBIR proposal to optimize the drug----like properties and conduct IND enabling studies of the lead compound. PUBLIC HEALTH RELEVANCE: Stroke is a major public health problem with a US mortality rate that ranks third behind other diseases involving the cardiovascular system and cancer. Recent data implicate hyperactivity of Ca2+/CaM- dependent protein kinase II (CaMKII), a major mediator of Ca2+ signaling, in ischemic damage. We aim to increase the brain penetration of our potent CaMKII inhibitors and test the optimized lead compound for efficacy in an animal model of human ischemic stroke.ischemic stroke.